Preheat the oven to 350°F. Line 2-3 baking sheet with parchment paper. Set aside.
Stir the flour, baking powder, and cinnamon together in a small bowl. Set aside.
Beat the butter on medium speed with either a hand or stand mixer until creamy. Beat in the sugars on high speed until combined, 20 seconds. Beat in the eggs on high speed until light and fluffy, about 1-2 minutes.
Stir in the flour mixture until combined. Stir in the oats and raisins.
Scoop and roll 1 tablespoons of dough, placing the balls of dough on the prepared baking sheets 2-3 inches apart.
Bake for 20-25 minutes, or until the edges are light golden brown. Let the cookies cool on the baking sheets for 3 minutes, then transfer to cooling racks to cool completely.
Once cooled, spread some marshmallow fluff between two cookies and place another cookie on top.